Line of Duty is based around an anti-corruption unit’s internal investigations of fellow police officers. Photograph: Unknown/BBC/World Productions

Line of Duty, Jed Mercurio's popular and critically lauded police corruption drama, will be returning to BBC2 for two more series.

The BBC confirmed on Tuesday that it had taken the relatively unusual step of commissioning two further series of the drama, which drew 3 million viewers to its series two finale last month.

Line of Duty, based around an anti-corruption unit's internal investigations of fellow police officers, will return with two new series of six one-hour episodes apiece.

The double commission will be well received by fans, with the show steadily increasing in popularity since it returned in February for a second series.

Line of Duty's audience grew from the 1.8 million who tuned in for the second season premiere, to a season-high 3 million overnight audience for the finale, rising to 4.1 million taking into account seven day catch up viewing.

Mercurio, the creator of medical dramas Cardiac Arrest and Bodies, which also featured protagonists grappling with the moral dilemmas thrown up by their profession, promised new guest stars and hinted that some characters from the first two series might return.

"We're profoundly grateful to the fans who not only watched Line Of Duty but also made it such a talking point, and to BBC2 for this rare and immensely flattering opportunity," he said.

"For series three and four, I can promise two explosive new cases for AC-12, new guest stars as police officers investigated for corruption, further twists and turns from the loose ends of series two, and maybe even some surprise reappearances."

The new series were ordered by acting BBC2 controller Adam Barker and Ben Stephenson, controller of drama commissioning, from the independent producer of Line of Duty, World Productions.

Stephenson said: "Line Of Duty shows what the reinvestment of money in drama on BBC2 has achieved – unique, powerful and gripping drama that gets the nation talking. Bringing it back for two more years is the easiest decision I have made."

Other commissions confirmed on Tuesday by BBC2, which celebrates its 50th anniversary on 20 April, were the return for a second series of comedy thriller The Wrong Mans, starring James Corden, and women's history series The World Made by Women.

Barker also announced a new comedy, Nurse, based on the eponymous BBC Radio 4 series.

The series, written by Fast Show veterans Paul Whitehouse and David Cummings, follows a community psychiatric nurse and her patients and relatives.

Other commissions include Beyond Human, a natural history series looking at animal senses, and War in Afghanistan, a two-parter analysing Britain's role in the conflict.

"These new commissions, from some of our most talented presenters, film-makers and writers, demonstrate the range and ambition we have for the channel as we look forward to the next 50 years," said Barker.

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